1. Field of the Invention
The present invention relates to a printer capable of printing on either single-sheet forms or a continuous form. More specifically, the invention relates to a printer capable of discharging the printed single-sheet forms to a position where the single-sheet forms are inserted.
2. Description of Related Art
Printers capable of printing either on single-sheet forms or a continuous form are known as described in Japanese patent application No. 3-286670. As shown in FIG. 15, this printer comprises a printing area; feed and pinch rolls 110A, 110B and 112A, 112B; a table 104; paper guides 114, 116, and 118; a continuous form feed mechanism 120; and a paper guide 102. FIG. 15 shows major components only, omitting the casing and other known parts.
The printing area comprises a printing head 108 for printing on paper sheets and a platen 106. The feed and pinch rolls 110A, 110B and 112A, 112B are rotatably arranged to feed single-sheet forms to the printing area. The table 104 is designed for single-sheet forms to be placed thereon so that the single-sheet forms can be inserted into the printer. The paper guides 114, 116, and 118 guide paper sheet forms for printing to the printing area.
The continuous form feed mechanism 120 comprises a pin tractor feeder of a well-known type for feeding the continuous form to the printing area. The paper guide 102 is arranged for swinging in the directions of arrows X and Y, as shown in the drawing, to switch the paper sheet feed path to either one of two feed paths, a single-sheet form feed path and a continuous form feed path. Therefore, when printing is to be made on the continuous form, the paper guide 102 is swung in the Y direction so that the continuous form is fed by the continuous form feed mechanism 120 to the printing area. When printing is to be made on single-sheet forms, the paper guide 102 is swung in the X direction so that the single-sheet forms are fed from the table 104 or an automatic paper sheet feeder to the printing area. The printed single-sheet forms are selectively discharged onto the table 104. Namely, the printed single-sheet forms are conveyed by the feed and pinch rolls 110A, 110B and 112A, 112B, according to the instructions of an operator, in the direction opposite the feed direction. They are guided between the paper guides 102 and 114, between the paper guides 114 and 116, and discharged onto the table 104.
In the type of conventional printers described above, however, the path for discharging the single-sheet forms onto the table 104 is not straight but curved to some extent in the vicinity of the paper guide 102. This is because the same path is also used as the path for the continuous form. As a result, paper jamming occurs. When a plural number of top-end bound paper forms are inserted from the table 104, and discharged after printing to the table 104, the bottom unbound ends of the forms might jam if they are obstructed or caught by the paper guide 102 located in the X-position.
It is therefore an object of the present invention to provide a printer capable of conveying paper sheets after printing back to the inserted position. They are conveyed in a stabilized manner without causing paper jamming along the reverse conveying path for discharge even when the printing is made on duplication slips.